Alkyl maleate-vinyl ester copolymer



1953 E. ARUNDALE ETAL 2,628,220

ALKYL MALEATE-VINYL ESTER COPOLYMER Filed June 15, 1951 3 Sheets-Sheet 1 40,000 I 4 GEL j '1 A.DEC.Y\ MALEATE-VINYL ACETATE COPOLYMER, 50C,. V NON-ACTIVATED CATALYST 30,000

b.D1= c.v\ MALEATE V mm. ACETATE CoPoLYMak-,4O"C.. 5 Qanucrnou OXIDATION Z5000 ACTlVATl'D. CATALYST u] Z 0! .1 20,000 3 U 5 0 7 5 15,00 u] a A If! fbv 0 2O 4O 60 5O iOO POLYMER FRAGTlON OF TOTAL. Pow/Mal F I G i Erzr'in Grandale t Fred EJak zes -53nvea ors Feb. 10, 1953 E. ARUNDALE ET AL ALKYL MALEATE-V INYL. ESTER COPOLYMER 3 Sheets-Sheet 2 Filed June 15, 1951 mf rh QJM dMSCzJOQO r1953 L n e v n 5 e n P. o .L w m M n an ma M n d x 5 E? b E. ARUNDALE ET AL ALKYL MALEATE-VINYL ESTER COPOLYMER Feb. 10, 1953 3 Sheets-Sheet 3 Filed June 15, 1951 Patented Feb. 10, 1953 ALKYL MALEATE -VINYL ESTER COPOLYMER Erving Arundale and Fred W. Banes, Westfield, N. J., assignors to Standard Oil Development Company, a corporation of Delaware Application June 15, 1951, Serial No. 231,825

13 Claims. 1

The present invention relates'to lubricating oil compositions and improved methods for their preparation. This application is a continuationin-part of Serial No. 41,676, filedJuly 30, 1948, now abandoned, and Serial No. 218,673, filed March 31, 1951. v

In a copending application, Serial No. 728,727, filed February 14, 1947, by J. l-I. Bartlett, there is disclosed an invention involving the preparation of lubricating compositions containing inaleate ester-vinyl ester type copolymers. Such copolymers are particularly useful in lubricating oils and the like to improve viscosity index'characteristics and to lower'their pour points. The copolymers have been found to be quite satisfactory for these purposes in various respects. However, prior to the present invention, difliculties sometimes have been encountered in the relatively poor shear stabilityof the copolymer. This is due, apparently, to the presence in such polymers of components of widely varying molecular weights.

Lubricating oils used under many conditions are subjected to high rates of shear and to extensive mechanical working. 'This is particularly true where high pressures and high speeds of the lubricated parts are involved. Under such conditions it is obviously desirable that all of the ingredients contained in such lubricants, such as pour depressants, viscosity index improvers, or

any other modifiers be highly stable against breakdown due to shear.

The copolymers used prior'to the present invention and prepared under the conditions set forth generally in the aforesaid prior application 0 of Bartlett have commonly possessed an average initial molecular weight of around 5,000 to 8,000, as determined by the Staudinger equation, m ole 0 111 a rweight:111(Vs/Vo')/C 3.13 10- where C is the concentration in milligrams of Polymer per cc. of diisobutylene, Vs is the viscosity in centistokes of a solution ofconcentration C, and V0 is the viscosity in ce'ntistokes of diisobutylene. Lubricants incorporating as modifiers the products of polymerization processes previously used seem to have certainlimitations:

weight until about to conversion was prior copolymers of alkyl maleate-vinyl ester type apparently are cross-linked to some degree-at any rate, the heavy ends are not efiective components so far as pour point depressing activity in paraflinic oils is concerned. Relatively high molecular weight of additive is desirable for viscosity index improvement, but even for the latter purposes, the very heavy ends are undesirable. They also appear largely to be the cause of the shear instability referred to above.

In view of the foregoing, it appears that a good lubricating oil should contain a more uniform copolymer, 1. e., one having a narrower molecular weight range and more nearly constant composition throughout the polymerization process, for optimum improvement in pour point and viscosity index. The distribution of molecular weight should not be unduly broad. In fact, it is desirable that there be definite limits both on the molecular weight and on the proportion of the high molecular weight end product. It is an object of the invention to employ as lubricant additive products of a polymerization process so controlled that the molecular weight is held within proper limits.

According to the present invention, it has been .found that the molecular weight of alkyl maleate-vinyl ester type copolymers can be made more uniform by. specific choices of copolymerization temperature, catalysts, and promoters. Also, if

" desired, the average molecular weight may be increased quite substantially without producing extremely heavy end products. Specifically, it has been found that copolymers suitable for addia molecular weight substantially above about 40,000 and that not more than 20%, preferably not more than exceed 25,000 molecular weight.

The copolymers are of the Ca to C alcohol esters of maleic acid or anhydride and vinyl acetate type. Homologous materials such as the corresponding itaconate esters, and alkylene acetates, etc., may also be used. Specifically, the C10 to C16 alkyl esters, such as the decyl, lauryl, Lorol B (C10 to C16 saturated aliphatic alcohol) of maleic acid or anhydride are preferred.

Other conditions being equal, it is generally found that the average molecular weight of a polymer or copolymer of the general type under consideration here increases as the polymerization temperature is lowered. Using ordinary cata ysts, however, it may not be possible to secure polymerization at all when the temperature is lowered substantially below a critical limit. Thus with decyl maleate-vinyl acetate (or Lorol B maleate-vinyl acetate) copolymerization, for example, using a peroxide catalyst such as benzoyl peroxide, polymerization which proceeds readily at 70 C. may not proceed at all at a slightly lower temperature, for example, of to 60 C.

By activating the catalyst, and especially by using a reduction-oxidation activation technique. the polymerization may be conducted at the lower temperature which produces higher average molecular weight. The resulting copolymer has higher average molecular weight in the initial stages of polymerization and, in addition, the molecular weight may be maintained more nearly constant throughout copolymerization. The

. comparison between the two processes mentioned.

as applied to decyl maleate-vinyl acetate copolymers with and without the activation technique, is shown graphically in Figure 1 of the drawings. It will be noted that the area under graph A, in the higher molecular weight range, is much greater than under graph B. The same behavior applies to Lorol B (mixed C10 to C16) maleatevinyl acetate copolymers.

Certain other factors, in addition to the particular catalyst and catalyst activator, appear also to have a marked effect on the quality and molecular weight of the polymer. Thus the choice of solvent and the ratio in molar proportions between the respective esters to be copolymerized exercise significant eifects on the final product. Under some conditions, molecular weight remains quite constant throughout the polymerization whereas under others it increases gradually at first and more rapidly as polymerizaticn approaches completion. Under still other conditions, the molecular weight rises rapidly and uniformly from the outset. Several examples of these varied phenomena are shown graphically in Figures 2 and 3 of the drawings. Figure 2 shows comparisons between promoted and non-promoted catalysts at different temperatures, and Figure 3 shows the relative effects of different diluents.

The invention may be further described in detail by reference to the following examples and the data which accompany them.

EXAMPLE I A copolymer of decyl maleate and vinyl acetate was prepared by combining these materials in 1 to 1 molar ratio using 15% by weight of a suitable diluent, In this particular example, the diluent was chloroform. Other diluents such as n-heptane, toluene, methyl ethyl ketone, diisobutyl ketone, isopropyl ether, ethyl acetate,

methylene chloride, and pyridine may be used, though not entirely equivalent in all respects. Using 1.25% by weight, based on the reactant materials, of benzoyl peroxide as catalyst, with 1.25% of benzoin and 0.05% of ferric laurate as promoters, with a polymerization temperature of 50 C., a product was obtained havin an average molecular weight of 16,500 Staudinger. The actual polymer obtained appears to contain about 0.8 mol of decyl maleate per mol of vinyl acetate. This composition was fairly uniform throughout the copolymerization. At 10.4% conversion, the ratio of decyl maleate to vinyl acetate was 0.79. At 44.2% conversion, it was 0.80, and at 83.5% conversion, it was 0.81.

EXAMPLE II The choice of solvent apparently has some effeet on the uniformity of composition and for this reason chloroform is preferred. See Figure 3. However, there are greater differences between promoted and non-promoted polymers produced at a given temperature than between polymers producedby identical methods in diiferent solvents. For comparative purposes, several copolymers of identical esters were prepared. In one case, when n-heptane was used as solvent, the ratio of decylmaleate to vinyl acetate was 0.87 at 2% conversion, 0.77 at about 5% conversion, 1.02 at 42.6% conversion, and 1.05 at 58.8% conversion, showing a wider variation in composition of the copolymer at various stages in the process than in the previous example. When a copolymer was produced in heptane at 70 C. by the conventional method, without activation, the ratio of decyl maleate to vinyl acetate in the product was 0.75 at 5.8% conversion. The ratio increased to 0.88 at 34.6% conversion, 1.22 at 52.7 conversion, and 1.28 at 62.0% conversion. Other differences in the effects of solvents are noted below.

The product of Example I, with an indicated molecular weight of about 16,500 Staudinger was added to a standard high grade SAE 20 motor oil base having a viscosity index of and a viscosity of about 72 S. U. S. at 210 F. The quantity or" polymer used was 2.9% based on the finished product. The viscosity index of the oil was raised to 148.

The treated oil just described was given a shear test by passing it times through a recycle viscometer at 300 p. s. i. g. The shear test showed a loss in viscosity of the treated oil of 11.4%.

EXAMPLE III By comparison, another vinyl acetate-decyl meleate copolymer was made with the aid of 1.25%.benzoin, 0.05% ferric laurate, and 1.25% benzoylperoxide catalyst, based on the weight of the reactants. Polymerization was carried out in the presence of 15% n-heptane, based on the weight of the final solution as a diluent at 50 C. This product had an average molecular weight of about 19,800 staudinger. When added in similar proportions to the base oil of Example I, i. e., an oil of 72 S. U. S. viscosity at 210 F. with a viscosityindex of 115, the viscometer shear test showed a breakdown of 17.6% as compared with 11.4% for the product of Example I. This may have been due in part, but not entirely, to the higher molecular weight. When another copolymer prepared in the presence of n-heptane diluent and having a molecular weight of only 14,700 was tested, it showed a breakdown in the same 0 at 2 As indicated above, the proportions of the two compounds to be copolymerized may be varied somewhat, but in general the ratios preferably are not far from equimolar. Thus the ratio ester. Their average molecular weight ranged approximately from 13,000 to 20,000. The high molecular weight ends were reduced in the promoted catalyst processes.

Table I 1 Reaction Percent M01 L s s i s Percent lolymer I T enp Solvent Polymer Wt V. I. on Polymer 1 A 50 CECIL". 2. 9 16, 500 148. ll. B 50 Heptanc. 2. 74 19, 800 145. 0 17. 6 80 3. 0 19, 300 148. 0 21. 6

70 CECIL-.- 5. 1 11, 000 140. 0 15. 5. 5

50 CECIL... 5. 3 10, 500 143. 8 7.0 l. l

CHCIQ. 6. 0 10, 500 143. 4 5. 8 0. 5

1 150 passes, 300 p. s. i. g.

should be no greater than 1 to 2 mole of the maleate ester to l to 2 mols of the vinyl ester, and

preferably the limits are considerably narrower.

temperature within the range of 30 to 60 C. o

with suitably activated peroxide type catalyst. Specifically, Lorol B or decyl maleate and vinyl acetate copolymers, of the general character and properties referred to in said prior application, have been prepared successfully at a temperature of 50 C. using benzoyl peroxide as a catalyst in proportions of 0.5 to 1.5% by weight based on the reactant monomers being polymerized. Under some conditions, the quantities may be as low as 0.1 or as high as about 5%. Ihis catalyst is activated by an oxidation-reduction type activator consisting preferably of 0.05% of an oxidizing agent such as ferric laurate, or more broadly 0.01 to 0.5%, and 0.1 to 5%, preferably 0.5 to 1.25% of a reducing agent such as benzoin. The effectiveness of the activator is clearly shown because in its absence no substantial polymerization would have occurred under ordinary conditions at the temperature employed of 50 C. By use of the activating materials, polymers have been prepared having average molecular weights ranging from 7,000 or less up to about 20,000. Most of these have been found to be both good viscosity index improvers and pour depressants and to have improved shear stability. While polymers of 12,000 to 20,000 molecular weight Staudinger are ordinarily preferred, those of considerably lower molecularweight, e. g., as low as about 7,000, are also useful when they are reasonably uniform in composition and in molecular weight.

Thus, polymers prepared at 50 C., using the activating materials and the catalyst mentioned above, have been found to be more stable in shear than copolymers prepared at 80 C., with the same catalyst and without the activator materials. The following table shows comparative data of several different samples of polymers prepared at various temperatures and blended in lubricating oils of viscosity of s. U. S. at 210 F. Losses in voscosity due to shear are indicated in the next to the last column. Compo- As mentioned in the aforesaid prior application, the alkyl maleate-vinyl ester copolymer described therein compared very favorably with commercial additives in improved viscosity index and has excellent pour stability in oil which is subjected to repeated fluctuation in temperatures above and below its-pour point. The product prepared as described above at a temperature'for example, of 50 0., using the promoted catalyst, retains these excellent properties while at the same time providing the additional advantage of excellent shear stability. The preferred composition of this present invention, having an aver age molecular weight between about 7,000 and 20,000, is required in smaller quantity than the higher temperature polymerization product for raising the viscosity index of a base motor oil of good quality from to viscosity index. This particular oil is a solvent extracted Mid- Continent crude, blended with a. small amount of a Pennsylvania bright stock. A straight Pennsylvania base oil of 100 viscosity index may be raised to 125 by less than 1% of the material of polymer A, Table I, whereas one base oil of Coastal Crude derivation had its viscosity index raised from 64 to 100 by the use of only 1.1% of the same polymer.

Polymers preparedv according. to the above example and having molecular weights of 8,000 and 20,000 showed good shear stability as determined by viscosity measurements of oil-additive blends after passes in arecycle viscometer at 300 p. s. i. g. The polymers of lower average molecular weight are superior in this respect. However, as previously su gested, it appears to be the heavy end polymers which cause the shear breakdown and the proportion in which these are present determines'the shear breakdown to' a large degree.

It will be observed that the percentage loss in viscosity is very low in the cases of the promoted catalyst polymers. In general, copolymers prepared at the lower temperature by use of an activated catalyst seem to show less breakdown than polymers of the same average molecular weight, repared at the higher temperature. This appears to be due to the presence of particularly heavy end components, i. e., products of very high molecular Weight, in the non-activated catalyst product. In Table I, above, the copolymer of 19,800 average molecular weight, prepared with activated catalyst at 50 0. showed considerably less breakdown than a copolymer of the same average molecular weight prepared at 80 C. without activation. The same was found to be true -'of copolymers having molecular weights of about 19,600 and 14,700. In the table, copolymer C prepared at 80 C. without activation, contained 27% 7 8 of a high molecular weight gel which was oil Table II insoluble. See Figure 1 of the drawing. The molecular weight range varied all the way from with 1 mm 2,000 to more than 40,000, with a considerable Without Promoters zoin and @0575 proportion above 25,000. 5 hum-t This reduction in proportion of high molecular Y1 m A Y n A Weight ends is an important as ect of this invene 1 0 5? tion. As shown in Figure 1, 1211311 the activated Percent Percent catalyst technique, only 15% of the polymer has a a molecular weight above 25,000, about 17% I1ZIIIII it 2; it 3; between 15,000 and 25,000, about 22% between gg hydl'ovm- 3,000 and 15,000, and about 46% below 3,000. It Dibenzaldiperoxldc uu 20 1, 000 11 e, 000 is desirable that not more than 20%, by Weight, Z ,3: be above about 25,000.

chloroform i the preferred solvent for poly- 15 merization, as suggested above, though others 5 to t Concentration o Ca a y 5- may be used. In composition A of Table I, a nzoyl peroxide, best results are ge y yield of 84% of copolymer wa obtained using cured by using concentrations of 0.5 to 1.25%. chloroform solvent and the activation technique The f w n a a w r s cur d usi an 5% at 50 c. Using heptane as the solvent under the concentration y weight of the monomers decy same conditions, the yield was only 74%. The maleate and vinyl acetate with 15% of chloroshear breakdown of polymer A wa 11,4% as form at 50 C. The .molar ratio of the reactants compared with 17.6% for the heptane solvent was 1 to 1. Benzoin and ferric laurate were used product, polymer B, which had a somewhat as promoters. The efiect of varying these is also higher molecular weight of 19,800. Another ow heptane solvent product of 14,700 molecular Table H! Weight prepared at 40 C. still showed a shear 7H breakdown of 14.4% and it required 3.75% to C PU Y LPN" 1 1 1 i raise the same oil of 115 viscosity index to 145. ill? ff i ;1 RPM-021E YEN W g-e en Notwithstanding the evident superiority of chlon, "1 1 F 1 151 0. a M2 i roform, heptane and other solvents listed above r't r gz i'clo ilalm i 1 t' i may be substituted therefor with reasonably sata Z 1 isfactory results. 1.2.5 l 1 1a 0 i 5 At higher temperatures, 6. g., 70 to 80 C. or 1 .,.l 2 higher, the reduction-oxidation activation tech- 1 Z 4" T1 nique appears to be less useful. In one test a 3 1 .41 1. 0 n2 product prepared using such technique had a 0.5 1. 1.1 7. g lower molecular weight and actually gave a lower if 1 1 yield than the unactivated catalyst at the same 011 1: f 1" 1 temperature. The reason for this is not entirely -10 L25 1 I clear, but it is believed that too active a catalyst 0' .I Y 1.5 0 starts too many nuclei for polymerization simul- 1 f i .1 7 taneously so that the molecular weight cannot 112: 1: I 1' 20 reach a very high value. A reasonably high 5 molecular weight product is required for lower- 1 ing the pour point and also increasing the vis- A cosity index of mineral lubricating oils. As in- The following table shows results, using a vinyldicated in Figure 1, the process of this invention acetate copolymer with an ester of nialeic acid reduces the lower molecular weight components prepared by reacting with rnaleic acid or anhyas well as the higher. so dride a commercial mixture of Ca to C10 aliphatic The peroxide catalyst preferred is benzoyl peralcohols having an average carbon chain length oxide, but the others such as acetyl peroxide, of about 13.5, predominantly saturated, obtained tertiary butyl hydro peroxide, dibenzaldiperoxide, from coconut oil and sold under the trade name aralkylhydroperoxide, tertiary butyl perbenzoate, Lorol 13 alcohol. These products were generally and the like, may be used as previously mensimilar to the decyl maleate vinyl acetate cotioned. The following table shows results of polymers. X.Y, a d p tively, were the benusing 1.25% of each of these at a temperature of aoyl peroxide catalyst, the benzoin promoter, and C., with and without promoters: the ferric laulate p mo Table IV Sam 0. r lkmction 1 Time I P ,1 I r o 2 -o "s.

Dl I 1 Hrs, i fildxltmt E 11 31 111 lmknt colitis 2.0 50 i 30 1 2 s i 2.2.5 0. 00 1111 50 1 2.5 1 0.1 1.0111 '50 120 511 2.5 i 0.05 37; -11 .10 21 2.38 ZN-1s 1 00.0.5 1 1,000 20 50 1 18 3.0 1 3.0 1 0.12 i 10; 20 .20 l :14 I 3.5 i :15 1 0.11 15 .0 12 1.0 1.0 1 0.10 1 ifiq 20 .50 22 0.0 1 :-:.0 1 0.12 R11; 20 00 l 22 i 15.5 1 1 02'] 20 08 I 21 E 3.0 r11 20 68 16: 5.25 "1.811

l o viscosity S. U. S. at 210 F. 013 20% blend in mineral oil of about -13 S. U. S. at

B Thickenod to a gel.

In the examples of Table IV, a light mineral oil diluent was used in Samples V-242-5, V-256, V-259-60. Chloroform was used (20 to 30%) in Samples V-254, 255, and 257 and a mixture, 35% chloroform, oil, in V-253.

In several of the examples given above, C8 to C16 alkyl maleate and vinyl copolymers were prepared at 50 C. with specific quantities of monomeric benzoyl peroxide, ferric laurate and benzoin. However, equivalent substitute catalysts and activators may be used as mentioned above and the temperature and other conditions may be varied somewhat depending upon the activity of the catalyst, the effectiveness of the promoter, and the type of solvent. Thus, the temperature may be varied from about 30 C. to about 60 C. The time varies, but ordinarily will be between and 48 hours. With benzoyl peroxide, the catalyst quantity may be varied from 0.1 to about 5% by weight, based on the total mixture. although the upper limit is usually about 3 to 1%. The ferric laurate may vary from 0.01 to 0.5% and the benzoin from 0.1 to about 5% on the same basis as indicated above.

Other combinations of catalysts and of oxidizing-reducing agents may be useful. For example, other peroxides such as p-chlorobenzoyl peroxide, p-bromobenzoyl peroxide, lauroyl peroxide, curnene hydroperoxide, and the like, may be used instead of benzoyl peroxide as the catalyst. Other ferric salts of oil soluble fatty acids such as oleic, stearic, palmitic and related acids may be used as oxidizing agents instead of ferric laurate. Various oil soluble reducing agents containing hydroxy or carbonyl groups, or both, may replace benzoin. Some examples of such compounds are acetol, diacetone alcohol, diacetyl acetone, and acetonyl acetone.

Although the foregoing description has referred particularly to maleate esters and vinyl acetate, other maleate, fumarate, acrylate, methacrylate, itaconate or aconitate esters may be polymerized alone or with vinyl compounds. In lieu of vinyl acetate, methacrylates, styrenes, alkylated styrenes, and various other esters may be used as set forth more fully in the Bartlett application Serial No. 728,727, mentioned above. The essential feature of the present invention is that polymerization, at an appropriate and suitable molecular weight distribution, may be reliably controlled. Temperatures may be used which are lower than those at which the peroxide catalysts are normally active by using the reductionoxidation type activators. By this means, the molecular weight spread is restricted.

Compositions of the type referred to above, may be used as modifiers for lubricating oils, and the like, in varying quantities as set forth more fully in the Bartlett application. In general, they are added in proportions of 0.01% to 20%, preferably not more than 5%.

What is claimed is:

1. A process of preparing alkyl maleate vinyl ester copolymers having the desirable characteristic of depressing the pour point of lubricating oils into which they have been incorporated which comprises copolymerizing a Cs to C20 alkyl maleate with vinyl acetate in the presence of an inert organic solvent and from about 0.1% to 5.0% by weight of a peroxide catalyst at a temperature of from about 30 to 60 C., saidcopoiymerization being promoted by about 0.01 to 5.0% by weight of a. ferric salt of a long chain fatty acid as an oxidizing agent and about 0.1% to 5.0% of an oil soluble organic reducing agent selected from the class consisting of benzoin, acetol,

diacetone alcohol, diacetyl acetone and acetonyl acetone as a reduction-oxidation agent activator combination.

2. A process of preparing alkyl maleate vinyl ester copolymers having the desirable characteristic of depressing the pour point of lubricating oils into which they have been incorporated which comprises copolymerizing a C10 to C16 alkyl maleate with vinyl acetate in the proportion of about 1 to 2 mols of the maleate with from 1 to 2 mols of the acetate in the presence of an inert organic solvent and from about 0.1% to 5.0% by weight of a peroxide catalyst at a temperature of from about 30 to 60 C., said copolymerization being promoted by about 0.01 to 5.0% by weight of a ferric salt of a long chain fatty acid as an oxidizing agent and about 0.1% to 5.0% of an oil soluble organic reducing agent selected from the class consisting of benzoin, acetol, diacetone alcohol, diacetyl acetone and acetonyl acetone as a reduction-oxidation agent activator combination.

3. A process of preparing alkyl maleate vinyl ester copolymers having the desirable characteristic of depressing the pour point of lubricating oils into which they have been incorporated which comprises copolymerizing the maleic acid ester of a mixture of alcohols having an average carbon chain length of 13.5, obtained on the hydrogenation of coconut oil with vinyl acetate in the proportion of about 0.8 to 1.25 mols of the maleate per mol of the acetate in the presence of an inert organic solvent and from about 0.1% to 5.0% by weight of a peroxide catalyst at a temperature of from about 30 to 60 C., said copolymerization being promoted by about 0.01 to 5.0% by weight of a ferric salt of a long chain fatty acid as an oxidizing agent and about 0.1% to 5.0% of an oil. soluble organic reducing agent selected from the class consisting of benzoin, acetol, diacetone alcohol, diacetyl acetone and acetonyl acetone as a reduction-oxidation agent activator combination.

4. A process of preparing alkyl maleate vinyl ester copolymers having the desirable characteristic of depressing the pour point of lubricating oils into which they have been incorporated which comprises copolymerizing a decyl maleate with vinyl acetate in the presence of an inert organic solvent and from about 0.1% to 5.0% by weight of a peroxide catalyst at a temperature of from about 30 to 60 C., said copolymerization being promoted by about 0.01 to 5.0% by weight of a ferric salt of a long chain fatty acid as an oxidizing agent and about 0.1% to 5.0% of an oil soluble organic reducing agent selected from the class consisting of benzoin, acetol, diacetone alcohol, diacetyl acetone and acetonyl acetone as a reduction-oxidation agent activator combination.

5. A process of preparing alkyl maleate vinyl ester copolymers having the desirable characteristic of depressing the pour point of lubricating oils into which they have been incorporated which comprises copolymerizing C10 to C16 alkyl maleate with vinyl acetate in the proportion of about 0.8 to 1.25 mols of maleate per mol of acetate in the presence of an inert organicsolvent and from about 0.1% to 5.0% by weight of benzoyl peroxide at a temperature of from about 30 C. to 60 C., said copolymerization being promoted by about 0.01% to 5.0% by weight of a ferric laurate as an organic oxidizing agent and 11 about 0.1% to 5.0% of-benzoin as a reductionoxidation agent activator combination.-

6. A process according to claim wherein from 0.01% to 0.1% by weight of ferric laurate and 0.5% to 1.25% of benzoin is used as the reduction-oxidation agent activator combination.

7.A process of preparing alkyl maleate vinyl ester copolymers having the desirable characteristic of depressing the pour point of lubricating oils into which they have been incorporated which comprises copolymerizing about 0.8 to 1.25 mols of decyl maleate with about 1 mol of vinyl acetate in the presence of chloroform as a solvent and from about 0.1% to 5.0% by Weight of benzoyl peroxide at a temperature of about 30 C. to 60 C., said copolymerization being promoted by about 0.01 to 0.1% of ferric laurate and 0.5% to 1.25% benzoin, said copolyinerization being continued for a period of time such that the copolymer product has an average molecular weight of approximately '7,000 to 25,000.

8. A oopolymeric product of an alkyl maleate and a vinyl esterv having the desirable characteristic of depressing the pour point of lubricating oils into which it has been incorporated which has been formed by copolymerizing a Us to C alkyl maleate with vinyl acetate in the presence of an inert organic solvent and from about 0.1% |to'5.0% by weight of a peroxide catalyst at a temperature of from about to C., said copolymerization being promoted by about 0.01 to 5.0% by weight of a ferric salt of a long chain fatty acid as an oxidizing agent and about 0.1% to 5.0% of an oil soluble organic reducing agent selected from the class consisting of benzoin, acetol, diacetone alcohol, diacetyl acetone and acetonyl acetone as a reductionoxidation agent activator combination.

9. A copolymeric product of an alkyl maleate and a vinyl ester having the desirable characteristic of depressing the pour point of lubricating oilsinto which it has been incorporated which has been formed by copolymerizing a C10 to C16 alkyl maleate with vinyl acetate in the proportion of about 1 to 2 mols of the maleate with from l-to 2 mols of the acetate in the presence of an inert organic solvent and from about 0.1% to 5.0% by weight of a peroxide catalyst at a temperature of from about 30 to 60 C., said copolymerization being promoted by about 0.01 to r 5.0% by weight of a ferric salt of a long chain fatty acid as an oxidizing agent and about 0.1% to' 5.0% of an oil soluble organic reducing agent selected from'the class consisting of benzoin, acetol, 'diacetone alcohol, diacetyl acetone and acetonyl acetone as a reduction-oxidation agent activator combination.

10. A copolymeric product of an alkyl maleate and a vinyl ester having the desirable characteristic of depressing the pour point of lubricating oils into which it has been incorporated which has been formed by copolymerizing the maleic acidester of a mixture of alcohols having an average carbon chain length of 13.5, obtained on the hydrogenation of coconut oil with vinyl acetate in the-proportion of about 0.8 to 1.25 mols of the maleate per mol of the acetate in the presence of an inert organic solvent and from about 0.1% to 5.0% by weight of a peroxide catalyst at a temperature of from about 30 to 60 C., said copolymerization being promoted by about 0.01 to 5.0%

by weight of a ferric salt of a long chain fatty acid as an oxidizing agent and about 0.1% to 5.0% of an oil soluble organic reducing agent selected from the class consisting of benzoin, acetol, diacetone alcohol, diacetyl acetone and acetonyl acetone as a reduction-oxidation agent activator combination.

11. A copolymeric product of an alkyl maleate and a vinyl ester having the desirable characteristic of depressing the pour point of lubricating oils into which it has been incorporated which has been formed by eopolymerizing a decyl maleate with vinyl acetate in the presence of an inert organic solvent and from about 0.1% to 5.0% by weight of a peroxide catalyst at a temperature of from about 30 to 60 C., said copolymerization being promoted by about 001m 5.0% by weight of a ferric salt of a long chain fatty acid as an oxidizing agent and about 0.1% to 5.0% of an oil soluble organic reducing agent selected from the class consisting of benzoin, acetol, diacetone alcohol, diacetyl acetone and acetonyl acetone as a reduction-oxidation agent activator combination.

12. A copolymeric: product of an alkyl maleate and a vinyl ester having'the desirable characteristic of depressing the pour point of lubricating oils into which it has been incorporated which has been formed by ccpolymerizing C10 to Cm allzyl maleate with vinyl acetate in the proportion of about 0.8 to 1.25 mols of maleate per mol of acetate in the presence of an inert organic solvent and from about 0.1% to 5.0% by weight of benzoyl peroxide at a temperature of from about 30 C. to 60 C., said copolymerization being promoted by about 0.01% to 5.0% by weight of a ferric laurate as an organic oxidizing agent and about 0.1% to 5.0% of benzoin as a reduction-oxidation agent activator combination.

13. A copolymeric product of an alkyl maleate and a vinyl ester having the desirable characteristic of depressing the'pour point of lubricating oils into which it has been incorporated which has been formed by copolymerizing about 0.8 to 1.25 mols of decyl maleate with about 1 mol of vinyl acetate in the presence of chloroform as a solvent'and from about 0.1% to 5.0% by weight of bcnzoyl peroxide at a temperature of about 30 C. to 60 C., said copolymerization being promoted by about 0.01 to 0.1% of ferric laurate and 0.5% to 1.25% benzoin, said copolymerization being continued for a period of time such that the copolymer product has an average molecular weight of approximately 7,000 to 25,000.

ERVING ARUNDALE. FRED W. BANES.

REFERENCES CETED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,047,398 Voss July 14, 1936 2,168,535 Nusslein Aug. 8, 1939 2,430,562 Gordon Nov. 11, 1947 FOREIGN PATENTS Number Country Date 487,593 Great Britain June 22, 1948 814,093- France 8, 1937 

8. A COPOLYMERIC PRODUCT OF AN ALKYL MALEATE AND A VINYL ESTER HAVING THE DESIRABLE CHARACTERISTIC OF DEPRESSING THE POUR POINT OF LUBRICATING OILS INTO WHICH IT HAS BEEN INCORPORATED WHICH HAS BEEN FORMED BY COPOLYMERIZING A C8 TO C20 ALKYL MALEATE WITH VINYL ACETATE IN THE PRESENENCE OF AN INERT ORGANIC SOLVENT AND FROM ABOUT 0.1% TO 5.0% BY WEIGHT OF A PEROXIDE CATALYST AT A TEMPERATURE OF FROM ABOUT 30* TO 60* C., SAID COPOLYMERIZATION BEING PROMOTED BY ABOUT 0.01 TO 5.0% BY WEIGHT OF A FERRIC SALT OF A LONG CHAIN FATTY ACID AS AN OXIDIZING AGENT AND ABOUT 0.1% TO 5.0% OF AN OIL SOLUBLE ORGANIC REDUCING AGENT SELECTED FROM THE CLASS CONSISTING OF BENZOIN, ACETOL, DIACETONE ALCOHOL, DIACETYL ACETONE AND ACETONYL ACETONE AS A REDUCTIONOXIDATION AGENT ACTIVATOR COMBINATION. 